Abstract

Non-self-sustained electric discharge and electric breakdown were triggered and guided by a train of ultrashort sub-TW ultraviolet (UV) pulses overlapped with a long free-running UV pulse of a hybrid Ti:Sapphire-KrF laser facility. Photocurrent sustained by this train is two orders of magnitude higher, and electric breakdown distance is twice longer than those for the discharge triggered by the long UV pulse only. When transporting the laser radiation over the long distance, UV filaments of ∼100 m length were observed.